Ruby spaceship operator <=>
What is the Ruby spaceship operator? Is the operator implemented by any other languages? ...
comparison-operators
What does "===" mean?
I recently studied some code that I'm supposed to use for different reasons, it's unrelevant. The thing I've noticed is someone using the operator "===" which I can't make sense out of. I've tried it with a function and it corresponds in crazy ways. The language is PHP by the way. Does anyone know what the definition of this operator i...
What is the reason for having 2 different "not equal to" operators in PHP?
I just happened to stumbled upon a piece of php code and could see author used <> to do a not equal to comparison: if ($variable <> "") { echo "Hello, I am having some value"; } I have always used !=: if ($variable != "") { echo "Hello, I am having some value"; } Are there any special circumstances, when I should use <> ove...
Is there a BASIC dialect which uses "==" as the comparison operator?
Anyone who grew up on BASIC, and later switched to another language, had a real difficulty getting used to "(a == b)" rather than "(a = b)" to test for equality. Is there a dialect of BASIC which uses the "==" operator for comparisons rather than overloading "=" for assignments and comparisons? Or - and maybe this is stretching it - is ...
Using comparison operators in SELECT clause of T-SQL query
How to select a result of comparison operator as a field with type BIT? How it does work in C#: bool isGreater = FieldA > FieldB; How it doesn't work in T-SQL: SELECT (FieldA > FieldB) AS BIT FROM t How to write such task properly? ...
Sorting By Multiple Conditions in Ruby
I have a collection of Post objects and I want to be able to sort them based on these conditions: First, by category (news, events, labs, portfolio, etc.) Then by date, if date, or by position, if a specific index was set for it Some posts will have dates (news and events), others will have explicit positions (labs, and portfolio). ...
Numeric comparison difficulty in R
I'm trying to compare two numbers in R as a part of a if-statement condition: (a-b) >= 0.5 In this particular instance, a = 0.58 and b = 0.08... and yet (a-b) >= 0.5 is false. I'm aware of the dangers of using == for exact number comparisons, and this seems related: (a - b) == 0.5) is false, while all.equal((a - b), 0.5) is true. ...
PHP compare doubt
if(0 == ('Pictures')) { echo 'true'; } why it's giving me 'true' ? ...
In Objective C, is there a difference between if (object == nil) and if (nil == object)?
I would lean towards if (object == nil) but I've noticed in some tutorials the use of if (nil == object) Is this just a style thing, or is there some justified rationale for using either format? ...
The importance of using === instead of == in php!
Today only I have noticed and found out the importance of using === operator. You can see it in the following example: $var=0; if ($var==false) echo "true"; else echo "false"; //prints true $var=false; if ($var==false) echo "true"; else echo "false"; //prints true $var=0; if ($var===false) echo "true"; else echo "false"; //prints fal...
MySQL - Why is COUNT with "greater than" quick but "less than" takes forever?!
SELECT count(*) c FROM full_view WHERE verified > ( DATE (NOW()) - INTERVAL 30 DAY) If I run that query it takes a split second but if I switch the comparison operator around it takes eons. Now the first way the count = 0 and the second way the count = 120000, but if I just count the whole table that also takes microseconds. But there...
invalid cast to type 'float'
I'm having problem with my class. I'm going to make comparision operators of my class. Some code: CVariable::operator float () { float rt = 0; std::istringstream Ss (m_value); Ss >> rt; return rt; }; bool CVariable::operator < (const CVariable& other) { if (m_type == STRING || other.Type() == STRING) int i =...
How to overload operator==() for a pointer to the class?
I have a class called AString. It is pretty basic: class AString { public: AString(const char *pSetString = NULL); ~AString(); bool operator==(const AString &pSetString); ... protected: char *pData; int iDataSize; } Now I want to write code like this: AString *myString = new AString("foo"); if (myString == ...
std::rel_ops functionality as a base class. Is that appropriate solution?
Hello, I've implemented the functionality of std::rel_ops namespace as a template base class (it defines all comparison operators using only operators < and ==). For me it's a bit weird that it works (so far) properly, also I'm concerned about the 'hacks' used. Can anyone assess the following code and say if I'm just lucky it to work or...
Checking if integer falls in range using only < operator
I need to come up with some code that checks if a given integer falls within the bounds of a range. (The range is represented by a pair of integers.) So, given a range r defined as an std::pair<int, int>, and a test integer n, I want to say: if (n >= r.first && n <= r.second) The catch is, I need to use a std::less<int> comparison fu...
comparison operator
hi, It may be silly question. Is there any way to give comparison operator at runtime using string variable. Suppose i have a data of salaries in vector. vector < int > salary; Input: salary[i] != /* ==,>,<,>=,<= (any comparison operator)) */ 9000. The input given like above. I store the comparison operator in string str. str = (an...